Display drive apparatus, display apparatus and drive control method thereof

1. A display drive apparatus for driving a display pixel connected to a data line, the display pixel includes a light-emitting element and a drive element in which one end of a current path is connected to the light-emitting element, the display drive apparatus comprising: a specific value detection section which obtains a specific value corresponding to variation of an element characteristic of the drive element; and a gradation signal correction section which generates a corrected gradation signal by correcting a gradation signal according to display data based on the specific value and applies the corrected gradation signal as a driving signal from one end of the data line to the display pixel, wherein the specific value detection section has a difference value detection section which detects a difference value composed of a value obtained by amplifying, with a preset amplification ratio, a difference voltage between a measured voltage and a standard voltage, said measured voltage is a detected voltage at the one end of the data line when a reference current is allowed to flow in the current path of the drive element on the display pixel via the data line and said standard voltage is corresponding to the magnitude of the reference current, and the specific value detection section obtains the specific value based on the difference value.

2. The display drive apparatus according to claim 1 , wherein the difference value detection section has a voltage operating section which has two input terminals including a first input terminal which is applied the measured voltage and a second input terminal which is applied the standard voltage, and obtains the difference voltage between the measured voltage and the standard voltage according to an operation, and outputs a value obtained by amplifying the difference voltage with the amplification ratio as the difference value.

3. The display drive apparatus according to claim 2 , wherein the voltage operating section includes a differential amplifier which has the amplification ratio, and the differential amplifier has the two input terminals and an output terminal to output the difference value.

4. The display drive apparatus according to claim 2 , wherein the specific value detection section has a correction data generation section which generates a correction data by converting a value into a digital signal, said value is obtained by dividing the difference value output from the voltage operating section by the amplification ratio, and outputs the correction data as the specific value.

5. The display drive apparatus according to claim 4 , wherein the gradation signal correction section includes: a storage circuit which stores the correction data output from the correction data generation section; a gradation voltage generation section which generates a gradation voltage having a magnitude to allow the light-emitting element to emit light with luminance gradation according to the display data; an offset voltage generation section which converts the correction data stored in the storage circuit into an offset voltage composed of an analog voltage so as to output it; and a voltage adjustment section which adds the offset voltage output from the offset voltage generation section to the gradation voltage generated by the gradation voltage generation section so as to generate the corrected gradation voltage and output it as the driving signal.

6. The display drive apparatus according to claim 5 , wherein the difference value detection section includes: a current source which outputs the reference current; and a connection path changeover switch which selectively connects an output end of the current source or an output end of the voltage adjustment section to one end of the data line, and when the connection path changeover switch is switched into a side where the output end of the current source is connected to one end of the data line, the reference current is supplied from the current source to one end of the data line, and a potential at the output end of the current source becomes the measured voltage.

7. The display drive apparatus according to claim 1 , wherein the standard voltage has a magnitude such that, when the drive element maintains an initial characteristic and the standard voltage is applied to one end of the data line, a current value of a current flowing in the current path of the drive element is equal to a current value of the reference current.

8. The display drive apparatus according to claim 1 , wherein the reference current is set to a magnitude necessary for allowing the light-emitting element to emit light with maximum luminance gradation.

9. A display apparatus which displays image information, comprising: at least one display pixel including a light-emitting element and a drive element in which one end of a current path is connected to the light-emitting element; at least one data line which is connected to the display pixel; and a data driving section which includes a specific value detection section which obtains a specific value corresponding to variation of an element characteristic of the drive element, and a gradation signal correction section which generates a corrected gradation signal by correcting a gradation signal according to display data based on the specific value so as to apply the corrected gradation signal as a driving signal from one end of the data line to the display pixel, wherein the specific value detection section has a difference value detection section which detects a difference value composed of a value obtained by amplifying, with a preset amplification ratio, a difference voltage between a measured voltage and a standard voltage, said measured voltage is a detected voltage at the one end of the data line when a reference current is allowed to flow in the current path of the drive element on the display pixel via the data line and said standard voltage is corresponding to the magnitude of the reference current, and the specific value detection section obtains the specific value based on the difference value.

10. The display apparatus according to claim 9 , further comprising: a display panel in which a plurality of select lines are arranged in a row direction, said plurality of data lines are arranged in a column direction, said plurality of display pixels are arranged near cross points between said plurality of select lines and said plurality of data lines, respectively; and a selection driving section which sequentially supplies select signals to said each select line and sets the display pixels on the respective rows into a selected state sequentially.

11. The display apparatus according to claim 9 , wherein the difference value detection section has a voltage operating section which includes two input terminals including a first input terminal which applied the measured voltage and a second input terminal which applied the standard voltage, and obtains the difference voltage between the measured voltage and the standard voltage according to an operation, and outputs a value obtained by amplifying the difference voltage with the amplification ratio as the difference value.

12. The display apparatus according to claim 11 , wherein the specific value detection section has a correction data generation section which generates a correction data by converting a value into a digital signal, said value is obtained by dividing the difference value output from the voltage operating section by the amplification, and outputs the correction data as the specific value.

13. The display apparatus according to claim 12 , wherein the gradation signal correction section includes: a storage circuit which stores the correction data output from the correction data generation section; a gradation voltage generation section which generates a gradation voltage having a magnitude to allow the light-emitting element to emit light with luminance gradation according to the display data; an offset voltage generation section which converts the correction data stored in the storage circuit into an offset voltage compose of an analog voltage so as to output it; and a voltage adjustment section which adds the offset voltage output from the offset voltage generation section to the gradation voltage generated by the gradation voltage generation section so as to generate the corrected gradation voltage and output it as the driving signal.

14. The display apparatus according to claim 13 , wherein the difference value detection section includes: a current source which outputs the reference current; and a connection path changeover switch which selectively connects an output end of the current source or an output end of the voltage adjustment section to one end of the data line, and when the connection path changeover switch is switched into a side where the output end of the current source is connected to one end of the data line, the reference current is supplied from the current source to one end of the data line, and a potential at the output end of the current source becomes the measured voltage.

15. The display apparatus according to claim 9 , wherein the standard voltage has a magnitude such that, when the drive element maintains an initial characteristic and the standard voltage is applied to one end of the data line, a current value of a current flowing in the current path of the drive element is equal to a current value of the reference current.

16. A drive control method for a display apparatus for displaying image information, the display apparatus including at least one display pixel including a light-emitting element and a drive element in which one end of a current path is connected to the light-emitting element, the method comprising: a step of supplying a reference current to the display pixel via a data line connected to the display pixel; a step of detecting a difference value obtained by amplifying, with a preset amplification ratio, a difference voltage between a measured voltage detected at one end of the data line and a standard voltage, said standard voltage is corresponding to a magnitude of the reference current; a step of obtaining a specific value corresponding to a variation of an element characteristic of the drive element based on the difference value; and a step of generating a corrected gradation signal by correcting a gradation signal according to display data based on the specific value so as to apply the corrected gradation signal as a driving signal from one end of the data line to the display pixel.

17. The drive control method according to claim 16 , wherein at the step of obtaining the specific value includes: a step of obtaining a value by dividing the difference value by the amplification ratio, and generating a correction data as the specific value by converting the value into a digital signal.

18. The drive control method according to claim 17 , wherein the step of supplying the driving signal to the display pixel includes: a step of storing the correction data in a storage circuit; a step of generating a gradation voltage having a magnitude to allow the light-emitting element to emit light with luminance gradation according to the display data; a step of reading the correction data stored in the storage circuit and converting the correction data into an offset voltage composed of an analog voltage so as to output it; and a step of adding the offset voltage to the generated gradation voltage so as to generate the corrected gradation voltage, and applying the corrected gradation voltage as the driving signal to one end of the data line.

19. The drive control method according to claim 16 , wherein the standard voltage has a magnitude such that, when the drive element maintains an initial characteristic and the standard voltage is applied to one end of the data line, a current value of a current flowing in the current path of the drive element is equal to the reference current.